Urticaria Pigmentosa

Excerpt

Mastocytosis is a disorder characterized by mast cell accumulation, commonly in the skin, bone marrow, gastrointestinal tract, liver, spleen, and lymphatic tissues. The World Health Organization (WHO) categorizes mastocytosis into 3 main categories—cutaneous mastocytosis, systemic mastocytosis, and mast cell sarcoma. The WHO then divides cutaneous mastocytosis into 3 main presentations. The first has solitary or few (≤3) lesions called mastocytomas. The second, urticaria pigmentosa, involves multiple, disseminated lesions. The number can vary widely, from less than 12 to more than 100 or even near-universal involvement. The last presentation involves diffuse cutaneous involvement.

Urticaria pigmentosa is the most common form of cutaneous mastocytosis in children, but it can also occur in adults. This condition is considered benign and self-resolving, often remitting in adolescence. Internal organ involvement is rare in urticaria pigmentosa, unlike adult forms of mastocytosis. What makes urticaria pigmentosa particularly distinctive is its tendency to manifest as small, itchy, reddish-brown, or yellowish-brown macules and papules, commonly referred to as urticaria or hives. These lesions typically appear in childhood and can persist throughout a person's life. The condition can vary in severity; although it is often benign, it may cause symptoms and complications related to mast cell activation. A thorough understanding of the clinical features, pathophysiology, and management of urticaria pigmentosa is critical for healthcare professionals to ensure accurate diagnosis and optimal patient care.